On Fri, 1 Aug 2003 08:01:15 -0600, "Will Self"
wrote:

This relates to this musical instrument I'm planning to build...

There are buttons (approx 7/8 inch diam) attached to 1/8 inch brass
rod shafts. I want the shafts to slide in bronze bushings. By the
nature of the instrument, the player will often be pressing near the
side of the button rather than in the middle. The bushing will
probably need to be about 5/8 inch long.

What do you recommend for the bushings? I can buy 1/4 inch bronze
rod from MSC and drill it out on the lathe. Or maybe a combination
of drilling and reaming? I guess this will depend on the 1/8 inch
brass rod I get, and how accurate it is. I can get brass rod from
MSC, also I see that RC hobby suppliers carry brass rod in various
small diameters.

Should I try to look into Oilite? This would probably be overkill, right?

All advice, suggestions, ideas, etc. will be much appreciated.

Will



Greetings Will,
Don't use bronze bushings with brass rods. They will tend to stick to
each other and will wear fast. Instead, use steel bushings. MSC sells
drill bushings which are hardened and polished in the bore. Polished,
hardened steel against brass is a pretty good combination. If the
steel bushings won't work (corrosion from moisture?) then plastic
bushings will also work real well. Nylon or delrin. Acetal plastics,
of which delrin is one, absorb much less moisture than nylon and so
won't swell in humid conditions. Here we go, 1/8 I.D. 1/4 O.D. acetal
tube, 60" long, $3.03. MSC# 63384697. Don't know how close they hold
the I.D., but it's cheap enough to buy and experiment. The O.D. would
need to be supported. Maybe drilling holes in the instrument will
work. You can also buy solid acetal rod and drill it yourself. You
will need to use a slightly oversize drill because the plastic drills
undersize.The hole size depends on how hot it gets when drilled, the
type of drilling lubricant (water is fine), how sharp the drill is,
etc.. Acetal can be turned and bored easily. I machine a lot of it and
hold +/- .0003" tolerance with temperature contreolled conditions.
Cheers,
Eric R Snow,
E T Precision Machine.